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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

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Comments 126651 to 126700:

  1. An overview of Greenland ice trends
    Re 34: I don't believe in a lag, either. I believe that glaciers begin to respond to climatic changes very quickly but, as Chris points out, they don't necessarily come to equilibrium quickly or even approach equilibrium at similar rates. Re 33: I haven't read any of the papers listed in this thread and I'm unlikely to do so. It's completely unclear to me what you're trying to say by citing the ones you do. I assume there are also papers that suggest there will be greater rises in sea level. The question is, downgrade from what and upgrade from what? Generally accepted estimates of climate sensitivity to 2xCO2 have changed little over time, but there are papers suggesting more sensitivity and there are papers suggesting less. Maybe a good research topic would be to review predictions of expected sea level rise, too, and see how these have changed. You think uncertainty is underemphasized, but IPCC AR4 found sea level rise prediction to be so uncertain that it ignored dynamic changes. I think your opinion on uncertainty is unfounded.
  2. Record high temperatures versus record lows
    It's interesting and to some extent fun but exactly whats the point? Given that temperature isn't a random system is there anything to be gained from looking for randomness. As can be seen from the graph highs and low do diverge after the 1980s to suggest warming but they also diverge in the 1960-1970 but in the opposite direction suggesting cooling for that period, statisical significance for both period would be interesting. To add to that I wonder what happens when, following a cold snap (1970s), you look for randomness in the distribution of highs and lows? Common sense would suggest you'd see more highs. An alternative analysis might be to analyse the data from the begining of each period (warming and cooling) to look for trends within that period although this would have the disadvantage of shorter time course.
  3. An overview of Greenland ice trends
    Steve One more point on lag. This is from the Rignot paper's conclusion "We reconstructed the Greenland ice sheet total annual mass budget from 1958–2007. The ice sheet was losing mass during the warm period before the 1970s, was close to balance during the relatively cold 1970s and 1980s, and lost mass rapidly as climate got warmer in the 1990s and 2000s with no indication of a slow down. Hence, the temporal variability in mass balance is significant and closely follows climate fluctuations. " Clearly he doesn't believe in lag.
  4. An overview of glacier trends
    David You may want to watch what you write on this website I got my wrists slapped for writing "outlandish comment" Chris It's funny I accuse you of confounding local and global and you accuse me of the same. Points i) and iii) did attempt to highlight specific local conditions something that should be irrelevant over an averaged global scenario. I have no problem with the general principle of warming air = melting ice. I have a problem with the degree to which the historical process is minimised by yourself in order to over emphasis what is occuring today. Take the use of the term accelerating retreat, used to describe the retreat from 1970s to the present. Technically accurate, suggestive of an extra ordinary process occuring over the past 2 decades but go further back in time and you realise what is happening is a return to a previous rate of retreat in the 1940-50 before the pause around the 1970's.
  5. Record high temperatures versus record lows
    Steve L @9, yes, that's what I meant. To me, comparing record high minima (night-time minimum temps) against record low minima - and, separately, record high vs record low maxima - would be much more significant than just high maxima vs low minima. Wonder if I can dig up the raw data and do that myself...
  6. An overview of Greenland ice trends
    Chris i) I see you're reviews in post #2. I don't have time to read everything but essential these papers are using the same sort of data (archaeological, salt marshes etc etc) which Grinsted uses when looking beyond the sea gauge data. These have all the same problem that you have pointed out previously- local, sporadic etc etc. ii) Accepted. It works both ways. Grinsted graph shows higher peak temp in the MWP than in the year 2000. It there on the graph. iii) I'm not sure that the temp rise was very slow and prelonged. Sure the rise started in 600Ad and end around 1200AD but according to the Grinsted graph most of the rise occured over a much shorter time period. I have a real problem with the attempt to compared the rate say over the past 20years with an average rate over a period of 600years, it seems inherently flawed to me. Better would be to compare similar time periods. Obviously the scale on the Grinsted graph makes the following a little dodgy but still i think it gives good ball park figures. We agree sea levels have risen 18cmm in the 20th century. Lets pick a 100 year period around the MWP. let go for 1000-1100AD as this is the time of steepest rise on Grinsteds graph. Print the graph to fit A4 paper and you can probably measure about 10cm of sea level rise for that century. That puts the rate about half the average rate in the 20th century if you accept the 18cm figure. Are you now suggesting a 200-300year lag in sea level rise? So we are seeing sea level rise due to climate conditions from 1710-1810? Does that mean the 14cm rise in 20th century sea level rise which is anthroporgenic is due to mans activity in the 17th century? There seems a logic in consistency in this process #Steve It's an interesting point you make about Chris point iii). Another thing that had occured to me is that if the 1960-1970 represented and static and in some cases reversal of glacier melt than that offers the possibility that come the resumption of retreat post 1970s there is the possibility of an exaggerated bounce ice is cleared fro I aplologise for the poor posts they are usually rushed in the time between experiments and tend to try to cover too many point (like this one). But part of the problem is that I think this science is far from complete, often publications contain contradictory statements, expressing that uncertainty is a problem for me. I think there is much more uncertainty in this process something that is often expressed by many of the better authors themselves. But many other are more cavelier. Take one of Chris' reviews from #2 Church JA et al. (2008) Understanding global sea levels: past, present and future Sustainability Sci. 3, 9-22. Reviews have time and space to look at all aspects of a subject but this review doesn't mention uncertainty in relation to historical data, a very important aspect. How about this paper GEOPHYSICAL RESEARCH LETTERS, VOL. 34, 2007 Meteorologically driven trends in sea level rise Alexander S. Kolker Which claims to identify important meteorological factors that affect apparent sea level rises independant of global mean temperatures. This paper also "downgrade rates of warming induced sea-level change along Atlantic shorelines" Or how's about this publication GEOPHYSICAL RESEARCH LETTERS, VOL. 31, 2004 Ocean freshening, sea level rising, sea ice melting Peter Wadhams et al which also downgrades 20th century eustatic rises.
  7. The albedo effect
    Henry Pool wrote "Apart from the radiation trapped and reflected by CO2 we also sit with the problem that cooling may occur higher up the atmosphere (CO2 freezes at -40 degrees C I think?). Obviously where it freezes it must reflect a lot more sunshine. (compare water vapor with water droplets - I am sure the droplet reflect more sunshine." No, CO2 does not freeze in the Earth's atmosphere. It does not even form liquid droplets. The partial pressure of CO2 in the Earth's atmosphere is far too low. "Partial pressure" is the pressure of CO2 if it were the only gas in the atmosphere. Since the total pressure of the Earth's atmosphere is (by definition) 1 atmosphere, and CO2 is on average 0.038% of the atmosphere, CO2's partial pressure in the Earth's atmosphere is on average 0.00038 atmospheres. At the higher levels of the atmosphere where the temperature gets low, the partial pressure is drastically lower even than that. You can see from CO2's phase diagram that it cannot possibly change from gas to liquid or solid at those pressures--not even at the Earth's surface, let alone high in the atmosphere.
  8. Record high temperatures versus record lows
    Proposed new website: "Father in-law Science". Matt @7, do you mean you'd like to see record high daily minima and record low daily maxima? I think I agree -- let's look at nighttime and daytime temperatures separately.
  9. Record high temperatures versus record lows
    It would be interested to see a similar analysis for Australia. The heatwave and other temperature records of Victoria and South Australia are being blown away year after year. Something really screwy is happening. Now we are seeing a heatwave in Spring that exceeds the record from a few years ago for summer heat waves.
    Response: It's funny you should mention that - Meehle 2009 refers to a similar study on record highs/lows being done for Australia. I scratched around for it but it appears to be not yet published - will add it to the It's Freaking Cold page when it comes out.
  10. Record high temperatures versus record lows
    Fascinating study, and well delivered - thanks. What would be especially interesting would be to see the data on record high maxima versus record low maxima, and particularly record high minima versus record low minima.
  11. The albedo effect
    Re 36, Henry: how can longwave radiation of the wavelength relevant to CO2 increase at the Earth's surface if CO2 is reflecting that out to space before it gets to Earth? I'm not going to go to much effort with you unless you're willing to think about this. In my opinion, you're not being taken entirely seriously here for the following reasons: 1. You make comments based on your own vague interpretations, 2. When asked for citations you make it hard for people to see what you mean and/or you cite things that don't make the point you pretend they do (both exemplified by the Astrophysical Journal abstract you quote in #28), 3. You seem to think that other people have to do things for you -- as SNRatio says, the burden is on you to be convincing, especially given all the evidence that there is an enhanced greenhouse effect (Venus is a good example of a high albedo but hot planet that you would have to explain). I think you can be more effective if you try to adjust your approach.
  12. Why is Greenland's ice loss accelerating?
    One more number to put the extra inflow into context. The 400 GTon/yr correspond to 1.3*10^4 m3/s which in turn translates into 0.013 Sv. Both the Labrador current and the east Greenland current are several Sv.
  13. An overview of Greenland ice trends
    Hi Chris, I think you've been quite clear that response time is about re-establishing equilibrium (ie the full response). I don't know how well HR distinguishes this from lag times, which I think for him are periods of nothing happening (no detectable beginning of a response). But I can't be sure, because I don't find HR's writing to be very clear. One thing I thought I should ask about your point (iii) above, surely as the amount of available ice left to melt decreases, the rate of sea level rise will decrease. We may be far from running out of ice, but it seems to me that ice retreating up mountains is harder to melt, and even a linear response in sea level could be expected from that. Or perhaps this is where the geography comes in, as land gets steeper as you go up? Maybe I should have limited my comment to: Can we say at what point in a steadily warming world sea level rise stops accelerating?
  14. The albedo effect
    To be clear, CO2 does reflect radiation at some wavelengths, but reflection is inconsequential for the Earth's current situation of global warming.
  15. The albedo effect
    Henry Pool, you wrote "as I have clearly shown you, over and over again I should say, CO2 also causes reflection of sunshine." That is incorrect, as several people repeatedly have told you," and even have referenced peer-reviewed scientific papers that you, yourself, can read. "Reflection" is a specific physical phenomenon that is qualitatively different from absorption-followed-by-emission.
  16. Record high temperatures versus record lows
    mea culpa - formatting errors: I wrote two posts too quickly, and have messed up a blockquote here: http://www.skepticalscience.com/An-overview-of-Greenland-ice-trends.html post #31 and a bold text closure here: http://www.skepticalscience.com/An-overview-of-glacier-trends.html post #24 my very bad! Is there any way of resetting the formatting to the default at the end of each post so that careless numpty's like me don't keep messing up the formatting?
    Response: Chris, I've manually fixed those two comments. There's probably some clever code I could write to automatically fix stuff like that but I'm too busy (and lazy) to dream that up at the moment so I'll just throw a bandaid on the problem for now :-)

    BTW, I've tried emailing you several times with no reply. Do you no longer use the o2.co.uk email address you signed up with or are you just ignoring me?
  17. The albedo effect
    Are these papers freely available to the public? Or are they hidden somewhere?? In any case why is it so difficult for anyone to show me the calculation as to how they came to that value of 1.7? You cannot do only measurements of downward longwave radiation because as I have clearly shown you, over and over again I should say, CO2 also causes reflection of sunshine. So you have to look at both.....and than you must report the net effect of the cooling and warming, if possible with measurements at various CO2 concentrations. Without the results of proper investigations into this, to say that we must reduce CO2 might be just as non-sensical as saying we must reduce water vapor or ozone (which are also greenhouse gases).
  18. Record high temperatures versus record lows
    There are three possibilities: 1) Global Climate stays the same. 2) Global Warming. 3) Ice Age. It was stated years ago that... "Nothing endures but change." http://en.wikiquote.org/wiki/Heraclitus If true, there are actually only two possibilities. And ironically, if we were heading for an ice age, the demand for burning wood and and fossil fuels would be on the increase.
    Response: That Heraclitus quote is apt - climate has and always will change, with or without human intervention. This is because when the planet is in energy imbalance - when it's accumulating or losing heat - temperature changes. Currently, CO2 is imposing an energy imbalance due to the enhanced greenhouse effect. So past climate change actually provides evidence for our climate's sensitivity to CO2.
  19. Record high temperatures versus record lows
    Well, I've now followed the link to the news release and found that fewer record lows (rather than more record highs) was general and expected (because nighttime temperatures are expected to increase faster than daytime temperatures). I have one more observation about the data, though: I think a better way to present such things would be to show the percentage of new records that are highs. 50% would be even, twice as many highs as lows would be 67% (rather than requiring a log scale in Figure 2). PS -- thanks cbrock, I just need to translate these pages. Any interest in translating your work, John? (Or maybe the common skeptic arguments are actually different ones in other languages.)
  20. An overview of Greenland ice trends
    (i) Not really HR. I was addressing your specific points re local, relative sea level. The data obtained fron the central latitudes re global eustatic sea level changes (see reviews/papers cited in my post #2) indicate that eustatic sea level variation has been small in the latter parts of the Holocene, once polar ice sheet decay reached near equilibrium with Holocene temperatures. (ii) You can't accept Grinsted's pre-industrial sea level variation without accepting their 21st century projection. They are intimately linked within the same model. (iii) Sea levels may well have been higher during the MWP compared to now. The temperature rise to the high point of the MWP was very slow and prolonged, and land ice melt was able to come close to equilibrium with the forcing (higher temperature). We're well above the MWP temperature now, but contemporary temperature rise has been so rapid that we've only surpassed MWP temperatures since the 1970's. It takes an awful long time for (especially) polar and glacier land ice melt to re-equilibrate with a change in forcing, and so the rise in sea level well above the MWP level will take some time. It's rather tedious that you don't read the papers you refer to but this is very obvious from Grinsted et al (2009): they state:
    The 12–21 cm higher sea level stand during the MWP is likely the highest sea level since the previous interglacial period 110,000 years ago, and was produced by an extended period of warming, allowing time for glaciers and thermal expansion to reach a climatic balance. Hence, the cooler than present temperatures in the MWP is consistent with higher than present sea level. Table 2 (T 0) shows that the sea level at 2090–2099 will be higher than MWP even with no rise in temperatures above the present.
    That's obvious isn't it HR? We've been discussing glacier response times on the other thread. These are generally of the order of 10-100 years (largely depending on glacier geometry). The sea level response time is larger than that since it's dominated by the slow component of polar ice sheet melt (there may be faster dynamic response components). e.g. going back to Grinsted et al:
    The inclusion of paleo-temperature reconstructions allows us to determine that present-day sea level rise is dominated by a fast 200–300 year response time to temperature
    (iii) Yes 18 cm sea level rise for the 20th century [14 cm, or nearly 80% of which was anthropogenic according to Jevrejeva et al (cited in post #28)]. Sea levels are currently rising at ~3.2 mm per year. So sea levels rose more slowly during the earlier periods of the 20th century than now. As temperatures rise the rate of sea level rise increases. That's obvious isn't it? As temperatures continue to rise, ice sheet responses will be driven towards ever increasing new equilibrium (denuded) positions, and the rate of sea level rise will continue to increase.
  21. Why is Greenland's ice loss accelerating?
    RSVP: In my opinion, no harm no foul. In regards to my calculations above, while it is probably moot, I will note that in fact, a portion of the melting would actually take place out of the water with the phase change being caused by above zero ambient temperatures (for the short while this actually happens) and what sunshine they get up there. I took a quick look to see if I could get a number for sunshine hours, but quickly realized it wouldn't give me what I needed anyway so I gave up. Regards John
  22. An overview of glacier trends
    re #22. As on the other thread you're playing fast and loose with the particular and the general and the local and global. One might think you were attempting to muddy what is a rather straightforward issue! If one samples over populations of glaciers, one finds that there is an overall glacier recession in a warming world (good examples in the USGS report you linked to) and advance in a cooling one. This is a sufficiently obvious and robust finding that one can use glacier recession as a crude "thermometer" of historical global temperature rise. One should incorporate what we know about glacier responses, as Oerlemans did (see paper cited in my post #21); he took account of the response time of the individuals glaciers studied, in other words the time it takes for glaciers progress towards the new equilibrium length/mass balance in response to temperature change (see [*] and papers by Oerlemans cited in my posts #15, and 21). Using glacier recession as a thermometer is bound to be a "crude" means of measuring global surface temperature (wouldn't you say?), but it's "obvious" that the straightforward relationship between glacier advance/recession and temperature (as in the USGS report you linked to) allows this to be done. Nothing wrong with including "crude" and "obvious" in a single sentence! Not sure what your insinuation re glacier response times is supposed to convey. This is a well characterized phenomenon, is specific to individual glaciers and can be assessed on an individual basis (see papers by Oerlemans cited in my posts #15 and #21 and [*]). If one wants to understand the relationship between temperature change and glacier response, we should assess response times and incorporate these into our understanding. You introduce a delicious false argument (with an interesting precedent) here: HumanityRules: "Your points i) and iii) seem to suggest that local, specific factors may dominate individual glaciers. If you accept that then really you can't make any general points about glaciers whether the data is to support one arguement or another." We could reframe your argument in the manner that it was used by antiscience propagandists of a recent generation, to highlight its deficiencies. If you assess cigarette smokers you'll find that their risk of contracting lung cancer relates to a number of factors outwith smoking that are both genetic and environmental (e.g. diet related). These latter factors are specific to the individual (highly "local"). One can then resurrect an analogous false argument by replacing a few appropriate words of your argument; e.g. "Your points (personal genetic/environmental factors) seem to suggest that local, specific factors may dominate individual lung cancer susceptibility. If you accept that then really you can't make any general points about smoking and lung cancer whether the data is to support one arguement or another". Do you see the deficiency in that argument HR? This relates to your focusing on the specific (individual glaciers or single specific local relative sea level as on the other thread) as if this negated the possibility of determining general trends by sampling over populations (and especially by taking into account what we know about the local factors). That’s obviously and crudely fallacious (apologies for using “obvious” and “crude” in a single sentence). You’ve made some odd misrepresentation of the text I pasted from the Solomina review: (i) 2003 in Europe was hot (we were in France that summer and it was definitely toasty). Solomina point out that those conditions would eventually cause most Alpine glaciers to disappear completely. Not very controversial. Your false précis of Solimina’s statement isn’t very interesting. (ii) Glaciers respond to changes in temperature. The response time is related to some rather well-characterised factors involving glacier geometry (e.g. the steepness of the glacial valley; its size). It’s silly to pretend that we don’t know about this. Try this paper [*] (or do some Googling), and work forward through the large number of papers that address this. (iii) If we want to understand natural phenomena we don’t dismiss what we know, and attempt to interpret observations in terms of caricatures denuded of meaningful detail. [*] David B. Bahr et al. (1998) Response time of glaciers as a function of size and mass balance: 1. Theory J. Geophys. Res. 103, 9777-9782
  23. Record high temperatures versus record lows
    Steve: Just point your father-in-law to this site--it worked for me with my father!
    Response: Skeptical Science helped convince your father-in-law? You've had better success than I. I've given up on my father-in-law as a lost cause. In fact, even my own father (also a skeptic) refuses to talk to me about global warming science (his argument is that he heard some guy on the radio say that the world was 5 degrees colder a few decades ago).
  24. Why is Greenland's ice loss accelerating?
    John Cross After re-reading what I wrote, I can see why you thought this, since I was not more specific... sorry about that. My mistake. I can assure you that that was not my intent. In any case, I did like your approach. I am also aware that my tone as pointed out by others went over the line and I will try hard not to let this happen again.
  25. Record high temperatures versus record lows
    Failing to look closely enough before my last comment regarding Pinatubo, I now notice that Pinatubo in Figure 2 didn't result in a large number of new lows. It just caused very few new highs (blue dot still a ways below expectation, red dot the lowest in the sequence).
  26. Record high temperatures versus record lows
    Another late night John! My father-in-law didn't believe in anthropogenic global warming, and we had a very animated and ineffective arguments about it. Now I'm told he has changed his mind! You might wonder, was it some new analysis or pedagogy or social attitude that got to him? Naw, it was hot where he lives last summer. I should tell him he's wrong to change his mind on that basis, but that probably won't do any good (we don't share any language in common, and I don't know how to mime the concept). I see Figure 1 and I first notice that the data appear to be distributed below the modeled expectation. Is there less stochasticity now (better measurements, for example), or is this just an artifact of the ln scale? Looks to be real to me. Also, is the number of stations constant throughout the study period? In Figure 2 there seems to be more interannual variation in later years (even excluding the obvious effect of Pinatubo). Perhaps when dealing with ratios, that's expected too, since it should be relatively easy to return to 1 or even less after a really hot year in the US. Or, hmmm, actually it would be interesting to remove the effect of Pinatubo from the trend, because that one cold year might really mute record cold temperatures going into the future. Sorry for the messy comment.
  27. High CO2 in the past, Part 2
    Actually, I think we are in agreement, as I have been using the coefficients calculated by Myhre et al (1998 and later papers) and used by the IPCC in 2001. Those are slightly lower that previously used figures. One possible explanation for Spencer's figure may be that he uses surface temperature instead of "effective temperature" for the calculation of his version of "Planck-lambda" to arrive at 0.18 instead of 0.27. But, in any case, he seems to be flatly wrong in asserting that it is not a controversial statement. And, as a climate scientist, is it possible not to know that.. For me, the most interesting about Royer's data is that the maximum basic net forcings hundreds of millions of years ago seem to be comparable to what we may be entering into now.
  28. Why is Greenland's ice loss accelerating?
    RSVP: to me it appears that you are trying to move your goalposts now. You initial post was obviously in regards to the globe and said nothing about the local temperature. I agree, it may have an impact on the local temperature (I would calculate the area of the sea around Greenland and compare it to the area of the whole ocean, but John Cook might make fun of my sums again ;-) ). However my main point was that no one is avoiding anything. Regards, John
  29. High CO2 in the past, Part 2
    Just a correction to the units in the last post: F of course is in W/m^2, and lambda in K/(W/m^2). Sorry for the typo!
  30. High CO2 in the past, Part 2
    Just a correction to the units in the last post: F of course is in W/m^2, and lambda in K/(W/m^2). Sorry for the typo!
  31. High CO2 in the past, Part 2
    I have a question about the basic CO2 forcing, as I would guess basic forcing may have been relatively more important as compared to the feedbacks at those high CO2 concentrations. As I have understood it, we have, as first order approximations and ignoring interactions, the two basic relations (C1 and C0 initial and final CO2 concentrations, respectively, 5.35 the coefficient used in IPCC AR3) forcing: F = 5.35 * ln(C1/C0) and temperature change: DT = lambda*F where lambda = 0.27 W(Km^-2)^-1. approx Giving about 1.1 degree K per doubling of CO2 as equilibrium effect of pure forcing. Is this the right way to do it? At CO2 concentrations of 5600 ppm, it would produce a (non-feedback) forcing of about 4.3 deg K, compared to recent pre-industrial levels, right? And, if it is, how, then can Roy Spencer write on his website (http://www.drroyspencer.com/global-warming-101/): "Now, you might be surprised to learn that the amount of warming directly caused by the extra CO2 is, by itself, relatively weak. It has been calculated theoretically that, if there are no other changes in the climate system, a doubling of the atmospheric CO2 concentration would cause less than 1 deg C of surface warming (about 1 deg. F). This is NOT a controversial statement…it is well understood by climate scientists. (As of 2008, we were about 40% to 45% of the way toward a doubling of atmospheric CO2.)" What have I (or, possibly, Roy Spencer) missed here?
    Response:

    The warming from doubling of CO2 is around 1.2°C (Lorius 1990) so you're not that far off. How does Roy Spencer arrive at "less than 1 deg C"? Unfortunately he doesn't cite how he arrives at that figure so I wouldn't know.

  32. Why is Greenland's ice loss accelerating?
    reply to John Cross Isnt it oversimplifying (and a bit unfair) to compare heat of ice melt in localized northern seas to that which is distributed throughout the entire planet's oceans? The energy can only cancel when these waters mix. This doesnt happen instantaneously, and less due to stratification. From any and all references Ive seen on the subject of Artic currents, if anything cold water seems to move outwardly away from poles. And these actually are changing over time as well. Ref example, "Arctic ocean currents shown to affect polar climate more than global warming" http://www.tgdaily.com/trendwatch-features/34866-arctic-ocean-currents-shown-to-affect-polar-climate-more-than-global-warming
  33. The albedo effect
    I have frequently asked the question as to where the 1.7 comes from, and did not get an answer. I read the IPCC report but did not get much the wiser other than to think (but I donot know) that it is a weighted figure. They look at the conc. of gases in 1750 and then do a weighting to 2005. Of course you can only do a weighting (=calculate proportional blame)if you are 100% sure what the cause is of a problem. If you donot have proof that CO2 is the problem (e.g. some stupid scientist like myself could not find it) you could be making a big mistake. At this stage I am not even sure if greenhouse gases are the cause of global warming.It seems to me no one did the right kind of testing. As to the integration problem: I was never any good at it, but should someone not have done a whole investigation into this and come up with a relationship that shows the net effect of the cooling and warming of CO2 at 0.01-.05%? The conc. is also important as relationships may change in certain concentration ranges. I think that is where ol Svante went into the mist. Also I think you cannot compare the radiation of the sun with earth, surely it cannot possibly on the same scale? Apart from the radiation trapped and reflected by CO2 we also sit with the problem that cooling may occur higher up the atmosphere (CO2 freezes at -40 degrees C I think?). Obviously where it freezes it must reflect a lot more sunshine. (compare water vapor with water droplets - I am sure the droplet reflect more sunshine.
    Response: The radiative forcing from CO2 is calculated using line-by-line models in two papers:

    Collins, W.D., et al., 2006: Radiative forcing by well-mixed greenhouse gases: Estimates from climate models in the IPCC AR4. J. Geophys. Res., 111, D14317, doi:10.1029/2005JD006713

    Forster, P.M.F., and K.E. Taylor, 2006: Climate forcings and climate sensitivities diagnosed from coupled climate model integrations. J. Clim., 19, 6181–6194.

    Of all the forcings considered to drive climate, CO2 forcing is one with a higher level of understanding. As for the evidence that CO2 is causing warming, this has been observationally confirmed both by satellites and surface measurements of downward longwave radiation.
  34. The albedo effect
    Henry, Integrate the incoming and outgoing radiation distributions for Earth over the actual absorption spectra and atmospheric concentrations, taking into account re-radiation etc. See what version of the radiation "discussion" is supported. Then compare with actual measurements, to see where consistencies and inconsistencies are to be found. It might also be illuminating for you to take a look at what the IPCC actually has to say, in scientific terms, when you are able to write such things as "the 1.7 assigned by IPCC to CO2 is from the idea: let us have a planet, let us add some CO2, see if the temp. goes up, it did, so that must be it." And the IPCC is of course open to new factors explaining the observed phenomena, if they can be rigourously established. But because we are always (Occam's razor) looking for the simplest models able to explain the phenomena, scientists may seem more arrogant towards new factors then they really are - it's just that is is the business of the proponents of new theories to furnish the evidence, not the opponents. This also makes science in a sense very conservative: When repeated attempts at falsifying a new theory fail, and it is both theoretically and observationally consistent with the existing body of knowledge, it will usually be incorporated in that body. Thereafter, it will be the business of opponents to point out errors, inconsistencies or wrong predictions. When you write "..the point is: you cannot go on the assumption that CO2 is the problem, because what else can it be? You have to provide me with scientific evidence," you seem to have overlooked these facts about how the scientific process works. The evidence is there, and the references cited on this blog is, I think, a great place to start. It's great if you can come up with even better explanations, but don't expect the proponents of an established theory to be very interested in working out your ideas, as long as they seem to work fruitfully within their paradigm.
  35. The albedo effect
    In the abstract it is explictly stated that they are comparing two nearby regions, one intact and the other after the fire. Other people made the observation that boreal forests reduces albedo and that cutting them down have a cooling effect. True, in the short term; and indeed the calculations in the extended abstract are done for one year only. But what is not considered in this kind of analysis is the time it takes to absorb again the emitted CO2. Indeed, in relatively few years, the regrowth of vegetation will bring the albedo back to the original value while the emitted CO2 will be in the air for many more years. If the forest was on average 100 years old it will take the same 100 years to bring the CO2 balance to equilibrium. In the meanwhile the excess CO2 will continue to have a warming effect and the older the forest the worst the impact.
  36. An overview of glacier trends
    "Honestly with a lag time of 4-36years you can fit just about any pattern to a data series which is less than 100 years" why does this sound familiar? Hmm, I know, because on an earlier thread a denialist was insisting that some mechanism involving the sun (decreasing in activity in recent years) was causing climate change because there was a time lag, using an analogy which seemed to involve hot plates and watched pots if I remember correctly. And yet here the whole concept of time lag, perfectly valid for glaciers whose form reflects a balance of losses and gains, is rejected out of hand by another denialist. Cherry picking, in denioworld, is not restricted just to data.
  37. The albedo effect
    Hi I'm looking for an explanation. I don't really get radiative forcing. Take this abstract on the nett radiative forcing effect of an Alaskan forest fire. The negative affect was 8 W/m2 while the positive affact was 21 W/m2. This seems a lot when "change of just 1% to the Earth's albedo has a radiative effect of 3.4 Wm-2" Is the abstract describing the nett radiative forcing for the area of the forest fire (7200hectares) while the 1% albedo figure is for the whole surface of the earth?
    Response: I haven't read the paper but I'm guessing the forest fire radiative forcing would be just for that region, not the whole globe. It would also be temporary. A global radiative forcing of 13 Wm-2 would be huge and have an immediate, sharp effect on global temperatures.

    The radiative forcing from a large volcanic eruption is quite large, particularly if it's located in the tropics so the aerosols from the eruption can spread through both hemispheres. For example, as discussed above, the global radiative forcing from Mt Pinutabo was  2.5 Wm-2. This is approximately equivalent to the radiative forcing of all human CO2 emissions since pre-industrial times. Global temperatures immediately responded to the negative forcing with global cooling happening. However, the effect was temporary - the aerosols washed out of the atmosphere and global temperatures bounced back after a few years.
  38. An overview of Greenland ice trends
    #28 Your right there was a lot of misunderstanding on my part. So from what you tell me the sparse historical data can tell us very little because it is only local relative sea level change. The potential for land movement means we can not rely on those measurements to tell us anything about absolute global sea level change. Then why continue to repeat the 1-10cm figure when it tells us nothing? Why not say we have no reliable measurable data before the 20th century. I now understand where you got the 50x figure from. I had misread the 21st for 20th. You didn't do what I asked and ignore the apocylyptic future. The point I was making with regard to the Grinsted graph was to do with the period upto the 20th century not into the future. This suggests that global sea levels were higher in the MWP than presently. Looking at the graph from Grinsted again there are areas of the graph at the run into the MWP were the slope (i.e. the rates of change of global sea level) looks very similar to the slope in the recent period. This rate slows up to the point that sea levels reach a peak. So there maybe periods in the MWP where rates of sea level change approached the rates of the last two decades. You suggest that sea level changes have been around 3.2mm/year for the past two decades with an average of 1.8mm/year for this century. Unless I misunderstand this, then that would mean a total of 18cm sea level rise for the 20th century? Back to Grinsted's graph. He shows about 30cm rise from 600AD to 1200AD. >40cm drop from 1200AD to 1700AD and then maybe >25cm rise from 1700AD to present. I'm unsure how you can square that with "The evidence simply doesn't support large variation in rates of global absolute eustatic sea level during the last 2000 years" when we are comparing that with the 18cm rise in the 20th century. (There is a little confusion for me in your quote above. Do you mean absolute changes or rate of changes?)
  39. An overview of glacier trends
    #21 This is from your #15 post "The dominant effect on mountain glacier recession/advance, polar ice sheet recession/advance and sea level rise and fall is temperature. This relationship is obvious to the extent that it’s possible to assign rather crude correlates of glacier advance/recession and historical temperature" I'm not sure whether the words crude and obvious should have been in the same sentance given the context but there is a suggestion in that remark that there was a correlate. Your points i) and iii) seem to suggest that local, specific factors may dominate individual glaciers. If you accept that then really you can't make any general points about glaciers whether the data is to support one arguement or another. I'm unsure what you mean in point ii) Honestly with a lag time of 4-36years you can fit just about any pattern to a data series which is less than 100years. How does lag work taking into account the often huge intra-seasonal variation in glaciers? Heres my crude understanding. This is a general scheme. Ice in glaciers can exist in areas where the air temperature will allow this. During the warming (summer) months the glacier retreats and in the cold winter months the ice can again flow further to regain some of the lost ground. Given that Fig5 in this Report suggests that intra-seasonal variation can be many multiples of the final nett annual change then how does lag work. In series of years with warming temperature how can glaciers ignore the warming weather to regrow each year and show no annual nett change. I can accept that for individual glaciers there may have specific local conditions that may allow deviation from a strong correlation of warmer air = retreating glaciers but its difficult to see how that occurs as a generalized phenomenon averaged of the global data (and this is what we are talking about). Your quote about European Alps in many ways sum up things for me. 1) An extreme summer of 2003 can be directly associated with 5-10% mass loss, where is the lag? 2) Many glaciers are responding quickly but conviniently some are taking upto 100 years to respond. 3) How do we every draw reliable averaged, global data when we continue to dismiss anything that doesn't fit into the theory with arguments ground local conditions. As a scientist I'd love to be able to dismiss the data that doesn't fit my theory it would make the whole process a lot easier.
  40. An overview of glacier trends
    #20 HR you're throwing out everything that we know about the phenomenon (glacier responses to forcings), and then trashing a simplistic caricature (your "simple relationhips"), which no one considers to be valid (i.e. that there should be a one-one contemporaneous correspondence between temperature variation and glacier response measurement). So in considering the relationship between glacier advance/retreat and global temperature, at least three relevant factors should be considered: (i) glacier response times to temperature change, (ii) the levels of volcanic aerosols to which glaciers are particularly sensitive and (iii) local geometric and climatic conditions that influence local glacier responses. Just considering glacier response times (since you tried to "head off" discussion of this rather obvious point!): Glacier recession will occur well after temperatures have levelled off from a warming phase, and recession can continue for a long time afterwards. This is because the glacier response is to the temperature difference from the previous "equilibrium", rather than to the temperature as it changes (see my post #15). Oerlemans recently estimated glacier length response times (which is somewhat similar to the time constant for an e-fold change for an exponential decay/rise), for several European glaciers, to be in the range between 4 years and 36 years (partly depending on the steepness of the glacial valley) [*] It's likely that the post 1940's glacial retreat that you mention was a continuing response to the warming to the 1940's, as the glaciers continued to respond to the temperature rise above the early 20th century temperature, even as the temperature rise stopped. Likewise, speaking of the European Alps, Solomina et al. (2007) [**] state:
    After a transitional time of modest gain since the 1960s, mass balances become strongly negative after about 1980. Most glacier tongues have started to react to this signal but are still far from a full dynamic response. Today – here in the sense of the year 2005 – tongues of medium-sized valley glaciers still reflect climatic conditions towards the end of the past century. In the meantime, average volume loss of Alpine glaciers has increased to about 2 to 3% per year. For a full geometric adjustment to the climatic conditions of 2000–2005, most glacier tongues and ice margins would require a farther retreat of a kilometer or more; and with repeated conditions of the extreme summer of 2003, most glaciers would disappear completely.
    "Simple relationships" do "begin to breakdown" if we pretend not to know what we know about them! [*] J. Oerlemans (2007) Estimating response times of Vadret da Morteratsch, Vadret da Palu¨, Briksdalsbreen and Nigardsbreen from their length records. Journal of Glaciology, Vol. 53, No. 182, 2007 [**] O. Solomina et al. (2008) Historical and Holocene glacier–climate variations: General concepts and overview. Global and Planetary Change 60, 1-9
  41. Why is Greenland's ice loss accelerating?
    The Labrador sea, for example, is warming. We can safely conclude that the influx of cold water from the extra melting of the Greenland ice sheet is not the dominant effect. It should be expected, indeed. The Labrador sea is pretty cold and adding water only a little colder does not change much. Also, it should be compared to the concomitant melting of the winter ice of the whole region; it's just a tiny fraction. Need to put "significant melting" into context. What is true is that it's not included in any of the current GCM models, given that to my knowledge none of them predicted this fast melting. What matters, instead, is the different salinity which is the driver of deep circulation. Very much like the whole arctic ocean, the Labrador sea is more salinity stratified than temperature stratified, being the temperature gradient small.
  42. Why is Greenland's ice loss accelerating?
    A more often put forward idea is that freshwater from the melted ice sits on top of the ocean water, stratifying it more, and it refreezes more readily. This may also be a bit of a negative feedback mechanism. Where did I read about it? http://www.skepticalscience.com/Why-is-Antarctic-sea-ice-increasing.html RSVP, I think the "gloomandoomer" comment was uncalled for.
    Response: Note that the stratification in the Southern Ocean may be unique to the region. When first researching increasing Antarctic sea ice, I encountered Zhang 2007 who explained that the warming Southern Ocean paradoxically could lead to less warm water upwelling to melt sea ice. I wondered why a similar effect didn't occur with Arctic sea ice which is sharply falling and contacted the author about it. He informed me that the stratification of water in the Arctic is different to the Antarctic, hence sea ice reacts in a different way to warming waters.

    Agreed re RSVP's comment - I would've deleted it due to the unconstructive tone but there were several interesting comments posted in response which I didn't want to waste (John Cross went to so much effort with his sums) :-)
  43. Why is Greenland's ice loss accelerating?
    3# "Going to a previous post by John we see that the increase in heat content of the ocean is about 18*10^(21) J/year." Yes, but not all round Greenland, whereas the ice melt is.
  44. Why is Greenland's ice loss accelerating?
    RSVP: looking at the Ice Mass Loss graph above and doing some quick calculations I get an average of about 222 Gt a year of ice loss over the past few years (when loss is the most). If you don't mind my long hand math, this works out to 222,000,000,000 tonnes per year of ice melted. Now, the latent heat of fusion of ice is about 334 J/gram or (again I apologize for the notation) 334,000 J/kg = 334,000,000 J/ton. we multiply this by our ice loss from above and get an annual heat required to melt the ice of 222,000,000,000*334,000,000=74*10^(18) J. Going to a previous post by John we see that the increase in heat content of the ocean is about 18*10^(21) J/year. Looking at the ratio it requires about 1/250 of the heat accumulating in the oceans to melt the ice. Nothing more than a drop in the bucket ;) Regards, John
  45. Why is Greenland's ice loss accelerating?
    With all that has been said about how much ice is melting, I have not seen any mention of how this might cool the oceans. If the volume of ice is so significant, the energy absorption it brings with it should also have some impact (at least in the short term), and thus to some degree provide a cooling feedback mechanism. I can understand how this topic might be avoided as it would not help gloomanddoomer positions.
  46. Skeptical Science housekeeping: Comments Policy
    How do you set up hyperlinks?
    Response: A HTML hyperlink is set up like this:

    <a href="http://www.website.com/">Hyperlink Text</a>
  47. The albedo effect
    1) you just don't want to understand. the atmospheric absorption bands (that shows the difference between the radiation measured on top of the atmosphere and the radiation that is measured at sea level) clearly shows you that oxygen/ozone and water vapor and carbon dioxide cause reflection of light (back to outer space!). 2) it is not I that is confused about what happens when a few photons are absorbed by the molecule. I notice you did not answer the question I raised on 127! Light has to keep moving. "absorption" is the word that confuses people because they donot understand that once the max. amount of photons are absorbed, the molecule becomes like a mirror at that wavelength band where it absorbs and has to reflect the light back in the band where is absorbs. The position of the molecule is random so you can expect at least 50% of the light in that wavelength band to be sent back to space. I am asking: what is the net effect of the cooling and warming properties of CO2 especially in the CO2 range of 0.01 -0.05%. Where are the test results? the 1.7 assigned by IPCC to CO2 is from the idea: let us have a planet, let us add some CO2, see if the temp. goes up, it did, so that must be it. And some viking who lived 100 years ago and whose calculations have been proven wrong. If he was right, earth should have been a lot warmer. There is no proof that CO2 causes warming. 3) Plimer might be right. Most volcanic activity takes place underneath the seabeds. CO2 comes from volcanic activities (which also produces heat to the water). the point is: you cannot go on the assumption that CO2 is the problem, because what else can it be? You have to provide me with scientific evidence. 4) one day you will find out you are wrong...
  48. An overview of glacier trends
    Steve "HR, it seems to me like you're trying to say that recent/current mass loss in alpine glaciers is a continuation of a prior process." I'm certainly saying that is a possibility. Lets split the past century up into sections based on global mean temperature change and glacier retreat. 1920s stable glaciers 1940s strong retreat 1970s stable glaciers 1980s onwards strong retreat 1915-1935 rising temperatures 1935-1975 steady temperatures 1975-1995 rising temperatures how can you directly relate these two processes? In the 1940s glaciers were retreating right in the middle of a period of stable global mean temperatures while glaciers were stable in the 1920s during a period of global rising tamperatures. Before anybody says there is a delay in the glacier reaction to global mean temperatures the state of glacier retreat nicely coincides with changes in mean global temperature from 1970s onwards. Something I guess John and Chris have been pushing. I just think that once one goes back in time past the 1970s simple relationships begin to breakdown.
  49. An overview of glacier trends
    HR, it seems to me like you're trying to say that recent/current mass loss in alpine glaciers is a continuation of a prior process. That's an analog of this argument: http://skepticalscience.com/coming-out-of-ice-age.htm but I think this argument is even worse when applied to alpine glaciers.
  50. An overview of glacier trends
    Mmmmm. See what I can do John!

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